Method and apparatus for conditioning air



Oct. 10, 1939. H. J. KAUFMAN 2,175,469 METHOD AND APPARATUS FOR CONDITIONING AIR 5 Sheets-Sheet 1 Original Filed Sept. 2, 1933 ra L INVE NTOR MPAM J05: PH/Qt/l-M N BY MORNEYS Oct.- 10, 1939. H. J. KAUFMAN 2,175,469

METHOD AND APPARATUS FOR CONDITIONING AIR Ordzinal F iled Sept. 2, 1935 s Sheets-Sheet 2 INVENTOR /fizA/v JOSEPH lfiwmu ATTRNEYS Oct. 10, 1939. H. J. KAUFMAN 2,175,469

METHOD AND APPARATUS FOR CONDITIONING AIR Original Filed Sept. 2, 1933 '5 Sheets-Sheet S INVENTOR MFA/*7 JOSEPH KwPMM BY ATTORNEYS Oct. 10, 1939. H. J. KAUFMAN METHOD AND APPARATUS FOR CONDITIONING AIR Original Filed Sept. 2, 1933 5 Sheets-Sheet 4 ATTORNEYS Oct. 10, 1939. H. J. KAUFMAN I 1 IBTHOD AND APPARATUS FOR CONDITIQNING AIR ori inal Filed Sept. 2, 1933 s Sheets-Sheet 5 INVENTOR file/w JOSEPH KAumA/v BY mun, #[My/Ji.

ATTORNEYS Patented Oct. 10, 1939 PATENT OFFICE METHOD AND APPARATUS FOR CONDITIONING AIR Hiram Joseph Kaufman, Detroit, Mich., assignor of one-half to George R. McKinney, Detroit,

Mich.

Application September 2, 1933, Serial No. 687,995 Renewed June 8, 1939 23 Claims.

This invention relates to a method and apparatus for conditioning air, and has to do particularly with efiicacious and practical apparatus for all season air conditioning.

One of the main objects of the present invention has to do with the dehumidification of the air by subjecting the same to the action of a dissolving hygroscopic agent, and preferably in two completely separate steps, the hygroscopicagent being of different form during each step and the air being preferably contracted during a portion of one of said dehumidifying steps.

Another object of the invention has to do with novel structure for positioning and supporting the hygroscopic agent, both in particle and solution form, whereby to prevent any clogging action and provide positive continuous flow or circulation. More specifically, this object includes the use of dehydrator pans so positioned as to present a dehumidifying zone-of relatively high vapor pressure so fabricated as to evenly distribute partially dissolved hygroscopic material over the surfaces of the pans.

Other specific features relative to the dehumidification step and apparatus include means so arranged that the dehumidification apparatus is continuously washed clean and also including means for breaking up the solution surface into fine streams and for positively preventing the clogging up and the formation of crystals in the drainage connections.

Other objects include the provision of means for. dehiunidifying the air without reducing the temperature of any portion of the air below the final temperature required, to transform the latent heat of the moisture of the air into the sensible heat of the air; to allow the use of a higher temperature cooling medium from that of the dew point of the air and the wet and dry bulb temperaure of the air; and also to increase the action of the ionic content of the air.

A further feature of the invention has to do with the automatic regulation of the dehumidification and humidification in heated and unheated enclosures over wide ranges of temperatures in various climates.

. A further object of the invention has to do with means for drying air for special purposes" by first dehydrating air by refrigeration and then dehydrating hygroscopically in two steps to obtain a specially dry air having a relative humidity lower than required for ordinary purposes.

A further object of the invention has to do with structure and mechanism for contracting and expanding conditioned air to control the temperature thereof.

A further object of the present invention relates to the absorbing of vapors from the air, preferably those which are soluble in water or 6 hygroscopic solution, and which have a vapor pressure higher than that of the hygroscopic material surface in contact therewith, and to remove dust germs, microbes, and foreign substances by contacting the air with a large 10 amount of wet absorbing surface.

Still further features include details of structure and the arrangement and combination of various parts of the air conditioning system and particularly the automatic control features thereof, including means for indicating and controlling relative humidity over a wide range of temperature, as will be more clearly set. forth in the specification and claims.

This application is a continuation in part of 90 my prior application Serial No. 645,832, filed December 5, 1932. e

In the drawings:

Fig. 1 is an elevation, partly in section, illustrating my complete flow and control system for conditioning air.

Fig. 2 is an enlarged perspective view of the means for controlling the relative humidity of the air over a wide range of temperature.

Fig. 3 is a perspective view of the solution dehydrator pans.

Fig. 4 is a plan view, partially diagrammatic, of the dehydrating unit.

Fig. 5 is a sectonal view taken on line 5--5 of Fig. 4. r Fig. 6 is a view similar to Fig. 1, but slightly modified in the arrangement of the units making up the main and auxiliary dehydrating zones.

Fig. 7 is a diagrammatic illustration of one adaptation of my air conditioning system to a 40' two room enclosure including a combination of controls for conditioning and blending air.

Fig. 8 is a view similar to Fig. 7 illustrating another method of air conditioning and blending.

Fig. 9 is a view similar to Figs. '7 and 8 but 45 illustrating a sort of combination between the systems disclosed in Figs. 7 and 8 and also including a different system of air circulation after being conditioned.

Referring particularly to Fig. 1, it will be 50 seen that the entire air conditioning apparatus is embodied in or with relationto an enclosure member In, which in general is the air conditioning and control unit. The manner and means for conditioning air depends entirely upon the normal physical properties of the air to be conditioned and, hence, this enclosure member I is provided with an inlet duct containing means for predetermining the flow and subsequent control of the air, said meanscompr'ising a removable filtering unit l2 containing spun glass, steel wool, or similar material, a humidostat unit I3, a duct type thermostat l4, and a relative humidity regulating device I5.

This device [5 is novel and unusual in that it indicates and controls the relative humidity of the air over a wide range of temperature as compared with the ordinary humidostat which is a measure of the relative humidity of the air at one temperature only.

Referring particularly to Fig. 2, this relative humidity regulating device l5 comprises a base I6, to which is attached a thermostatic element I1 and a hygroscopic. element l8, said last element l8 being adjustably connected by means of an adjusting screw IS. A control lever is pivotally connected as at 2| with the hyroscopic element l8 and is also pivotally connected as at 22 with the thermostatic element |1, pivot 22 being adjustable through the medium of the slidable block 23 and adjusting screw 24. The adjustable screws l9 and 24 are more or less diagrammati cally shown, but it will be'understood that any type of adjusting element may be used to allow for mechanical defects and changes due to use over a relatively long period of time.

The hygroscopic element l8 may be formed of wood, parchment, human hair, or similar material, and the thermostatic element I1 is preferably formed of gutta percha, metals, ebonlte,

column mercury or gas, or similar materials. The projecting end of the lever 28 may be moved up or down by the changing tension of the hygroscopic element 8, or by the changing compressionci the thermostatic element l1, as a result of changes in vapor pressure or temperature of the air entering the duct l I. The end of the lever 28 is provided with a positive contact member 25, supplied with electric current by the positive lead in wire 25, the contacting point 25 being insulated by the insulating material 21 and in its normal operation contacting with the negative switch point 28, the latter being insulated by means of insulating material 29, mounted on a fixed base 30. The contact member 25 when moved in the opposite direction makes contact with a negative switch point 3|. Movement of the arm 20 in one direction or the other to contact with the switch members 28 or 3| will control actuation of suitable dampers, as will be subsequently described. r

A cooling and dehydrating coil 32 is located to the rear of the relative humidity regulating device I5 and may be supplied by cold water from a city main or a cold circulating medium from a refrigerating system or the like from the pipe 33 which, in turn, is controlled by a motorized valve 34 connected into the thermostat l4. The main supply of water or cooling medium passing through the coil 32 is conducted away through the pipe 35 while a portion of said cooling medium, as in the case of water, flows through a bleeding line 36 controlled by a hand valve 31. A portion of the inlet duct ahead of the dehydrating coil 32, is fabricated to form a ledge 38, and the'innermost end is provided with a drip edge 39 whereby moisture condensed from the incomingair will flow over the edge 39 and will be prevented from flowing back into the air inlet duct One of the main features of the present invention resides in the utilization of hygroscopic material in particle form and in solution form, the material being so arranged and supported in combination with'other means as to form two distinctly separate dehumidification zones. As best shown in Fig. l, a zone 40 is positioned opposite the air duct II and is provided with a plurality of solution dehydrating pans 4|, horizontally positioned and spaced one above the other whereby the air flow over the pans is horizontal. Each pan is relatively shallow and provided with a back wall 42 and side walls or edges 43 and 44, said walls 4.3 and 44 ,being attached to the side walls of the zone or compartment 40. The forward edge of each pan is bent downwardly at 45 and terminates in a plurality of notches 46 for breaking up the hygroscopic solution into small streams. The dehydrator pans 4| are progressively larger in size and surface area, the smallest pan being positioned at the top. By so arranging and positioning the pans, it will be seen that a relatively large surface area is presented for dehumidification purposes, and that each pan is continuously provided with hygroscopic solution. Water pans 41 are similar in structure to the pans 4| except that they are preferably of the same size and placed directly one over the other.

One of the features of the pans 4| is that each pan has an equal area exposed to catch the partly dissolved hygroscopic material (the source of which will be presently explained) so as to evenly distribute the said partly dissolved hygroscopic material over the surfaces of the solution dehydrator pans 4|. Flow of. air through the preliminary dehumidification zone or compartment 40 may be in general horizontal and then vertical or may be wholly or in part horizontal so that the flow of air is past the pans 41. Eliminator plates 48 are preferably positioned adjacent the pans 41 to form the air into tortuous passageways. A drainage pan 49 is positioned beneath the pans 41 and the plates 48 and is provided with a drainage funnel 50 and drainage pipe 5| leading to a collecting tank 52 which in turn is provided with a drain pipe 53.

The pans 41 are supplied with water, preferably hot water,, through a pipe 54 controlled by a motorized valve 55, which in turn is controlled by the humidostat l3. Damper members 56, 51 and 58 open or close communication between compartment 48 and a compartment 53.

Air normally passes upwardly from the zone 40 into a blending subdivision zone 80, separated from the zone 40 only by a screen 8|. Separate air may be admitted into the blending zone 83 through a damper 62 which admits air from the inlet duct 53. Air from this same duct 83 may be also admitted directly into the compartment 58 through the medium of a damper member 84.

From the'blending subdivision air passes upwardly into a particle dehydrator 65, the design and arrangement of which plays an important part in the practical operation of my complete air conditioning unit. In general, this dehydrator contains what might be called one large mass of hygroscopic material 86. This dehydrator 65 is provided with a plurality of passageways 1| defined by vertical screen members or perforated metal surfaces 12 which form what might be called baskets for containing hygroscopic' material. A screen member 69 preferably extends across the bottom of the dehydrator and is supported by a suitable frame memand to the damper motors 18 and 19; and also ber 18. A wire screen and frame 13 extends across the top of the dehydrator 65. The general parallel compartments thus formed for receiving the hygroscopic material are preferably formed as shown in Fig. 4, so as to present zigzag surfaces, with the result that one substantially rectangular column of air contacts with a portion of the hygroscopic material contained in four separate columns, thus presenting an extremely and eflicacious large surface area. It will thus be seen that the hygroscopic material may be I fed into the top of each of the compartments and that the air passageways 1| provide a complete passageway for the air.

The hygroscopic material is preferably calcium chloride or magnesium chloride in particle form. Such material, when it absorbs moisture from the air, tends to clog, but it will be seen that I have prevented any tendency to clog by providing completely free passageways entirely through this large mass of hygroscopic material. Likewise, the partly dissolved hygroscopic material is free to drip from the particle dehydrator 65 downwardly through the screen 6| and on to the solution dehydrator pans 4|, in a counter flow to the normal flow of air.

' The particle dehydrator 65 is partly divided by a partition member 14 and. the hygroscopic material may be fed to thedehydrator on both sides of said partition member through doors diagrammatically indicated as at 61 and 68-. This partition 14 extends generally upwardly to the top of the enclosure I8 and is provided with an opening for receiving damper members 16 and 11. 'These damper members are controlled by a damper motor 18 which in turn is controlled by the relative humidity regulating device I5. It should also be noted here that the passageways 1| are upwardly contracting to provide more efficient wiping action between the air and the surface of the hygroscopic material.

A second damper motor 19 controls the opening and closing of the dampers 56, 51 and 58, and as will be understood by those skilled in the art, the damper motors 18 and 19 are so interconnected as by means of a relay or cam action whereby after damper motor "I8 has been actuated to close the dampers 16 and 11 for more than a predetermined length of time, the damper motor 19 will be actuated to open the damper members 56, 51 and 58. In normal practice, the dampers 1'6 and 11 will open and close without afiecting the damper motor 19.

The compartment 59 also contains a blower 88 contained within the housing 8| and forming the entrance of a. contracting U-shaped air duct 82. A cooling coil.83, preferably supplied with cold water through pipe 84 controlled by a motorized valve 85, which in turn is controlled by the thermostat I4, is positioned in the duct 82, and the spent cooling medium returned to the source of supply or wasted away, as the case may be, through a return pipe 86. The U-shaped duct 82 terminates in a housing 81 containing an air turbine wheel 88 from where the air expands into an air outlet duct 88.

The blower 88 and turbine 88 aremounted on shafts 88 and 82, respectively, of a motor 9|, the entire unit being supported on a suitable frame 83. Electric power for the entire system is brought in through wires 94 and through switch 86 to a low voltage transformer 91 and then to the motor starting switch 98. From the transformer 91, current 'is carried by means of the positive wire 26 to the valve motors 34, 55

to the magnetic relay switch 99 controlling the current to said electric motor starting switch 88. Three wire control lines, including the positive wire 26 and two negative wires I88 and |8| are carried from the humidostat I3 to the hot water control valve 55; the positive wire 26 and the two negative wires I82 and I83 lead from the thermostat I4 'to the cold water control valve 34; the positive wire 26 and negative wires |82A and |83A lead from said cold water valve 34 to the cold water valve 85; the positive wire 26 and negative wires |82B and I833 lead from the cold water valve 85 to the magnetic relay switch 99; the positive wire 26 and negative wires I84 and I85 lead from the relative humidity regulating device I5 to the damper motor 18; and the positive wire 26 and two negative wires |84A and |85A lead from the damper motor 18 to the secondary damper motor 18.

In the operation of the complete all year round unit as shown in Fig. 1, the action of the hygroscopic element I8, which is in tension and which is afiected by the changes in the absolute humidity ofthe air, is modified by the compensating action of the thermotactic element 1, which is afiected by changes of the temperature of the incoming air, and which is in compression to control the relative humidity over a wide range of temperature of the air,

When it is desired to condition air for any given space, such all is drawn into the air duct I I and can travel three different routes withi the air conditioning apparatus, depending entirely upon the condition of the incoming untreated air as to its absolute humidity, its relat ve humidity, and its temperature. The control units I 3, 4 and I5 will be affected by the condiof the air. The cooling and dehydrating coil 32, when in operation, is cooling at all times and dehydrating only when the dew point temperature of the air is above the temperature of the coil 32, it; being understood that the cold Water flow within the pipe 33 is in counter flow to the incoming air flow and moisture separated from the air by the coil 32 collects on the plate below the c il and drips from the edge 39 into the collecting tank 52. A portion of the warmed water taken from the bottom of the coil 32 by means of the zone 48 where it passes horizontally over and between the solution deyhdrating pans 4| which are so arranged as to evenly catch the partly dissolved hygroscopic material 66A dropping from the particle dehydrator 65, through the blending subdivision '68, which in turn holds any-undissolved material 66A until completely dissolved by moisture absorbed from the air passing over it. It will thus be seen that the dehydrating solution 66A flows in an opposite direction to that of the incoming air; the plurality of notches 46 formed at the edges 45 insure that the hygroscopic solution breaks up and flows from the pans in a series of small streams and against the horizontal air flow into the collecting tank 52,

Under certain conditions the air also passes over and between the hot water pans 41, which are supplied with hot water through the pipe 54 controlled by the motorized valve 55 when the 15 absolute humidity of the incoming air falls below the fixed minimum setting as arranged on the humidostat l3. It will be understood that the flow of hot water through the pans 41 will take place usually in the winter season.

It will thus be seen that. conditioned air may be drawn into the compartment 59 through three separate routes. In the first or main route the air is drawn from the zone 48 up through the screen GI and into the blending subzone 60 where the treated air can be blended with another separate untreated air introduced through the inlet duct 63. Air is drawn up from the subzone 68 into and through the contracting air passageways H of the particle dehydrator 65 where the air contacts with the hygroscopic material 66 through the interstices of the screen or metal to allow the absorption of moisture from the air and to allow the partly dissolved hygroscopic material to fiow into and along the sides of the contracting passageway 1| and to flow by gravity in a direction opposite to that of the direction of the air. Due to the dissolving action of the hygroscopic agent and the absorption of moisture from the air by the partly dissolved solution, the latent heat of the moisture absorbed is converted into sensible heat and added to the air thereby increasing the temperature of the air and increasing its natural flow. In this first route the air is drawn through all the portions of the contracting air passageways 1| due to the closed position of the dampers 56, 51 and 58 and the open position of the dampers 16 and 11.

In the second route, the air is drawn up through the blending subzone 60 and into and up through a small portion of the contracting air passageway H to the right of the partition 14,.

Regardless of the route taken by the air during conditioning, the air will, upon reaching the blower 80, be blown downward and compressed in the contracting air duct 82, where the temperature is decreased and the super-heat removed by mea ns of the cooling coil 83. The air is then forced upwardly into the turbine 88 where a portion of the built up air pressure is used to reduce and offset the power load of the blower 80 and the compressed air expanding into the duct 89 will cause an appreciable lowering of the temperature of the air.

It will be seen that with a lowering of the relatlve humidity of the incoming air, the relative humidity regulating device -I will be actuated and cause the motor 18 to close the dampers 16 and I1, the dampers 56, 51 and 58 remaining closed, thus drawing all the air from the zone 40 up through the smaller portion of the main dehydrator zone, to the right of the partition 14, to decrease the dehumidification of the air. Upon a still further lowering of the relative humidity of the incoming air, the same regulating device 15 will continue to actuate the motor 18 and subsequently cause actuation of the motor 19 to open dampers 56, 5'! and 58, thus drawing all the air from the zone 48 directly into the zone .moved from the shaft 92 for winter use.

59 to further decrease the dehumidification effect ofthe system. 'By-a still further" lowering of the relative humidity and also of the absolute humidity of the incoming air, the humidostat l3 will be actuated to in turn actuate the valve 55 to allow hot water to fiow into the pans 41 to increase the humidity of the air.

The theoretical comfort zone is bounded by lines of relative humidity, maximum '70%-minimum 30%, with an ideal maximum of 60% and an ideal minimum of 40%. It will thus be seen that with a rising relative humidity from the conditions above set forth, and also the absolute humidity of the incoming air, will first result in stopping of the flow of water through the valve 55; with a further riseof relative humidity the regulating device 15 will actuate motors l8 and 18 to 'cause closing of the dampers 56, 51 and 58 and, subsequently, with a still further rise of relative humidity cause opening of the dampers l6 and I1.

With arising temperature of the incoming air, the thermostat l4 will be actuated to operate the valve 34 to-cause cold'water or other cooling fluid to flow through the cooling and dehydrating coil 32, the motorized valve 34 in turn causing the motorized valve 85 to open allowing cold water to flow through the cooling medium 83, and means within the valve 85 to in turn actuate the magnetic relay switch 99 to close the circuit supplying power to the motor starting switch 98 to actuate the motor and in turn actuate the blower' and air turbine.

When used for winter air conditioning it will, of course, not be necessary to fill the particle dehydrator 65 with material, and the coil 83 may then be supplied with steam or hot water;

the same thermostat l4 can be used to control the steam or hot water motorized valve, similar to the valve 85. The air turbine 88 should be re- The incoming air passage into and through the air conditioning apparatus is the same in all instances except for a small adjustment of the air temperature and humidity devices for the control of the temperature, the absolute humidity and relative humidity to conform with the desired winter comfort zone.

In the modification diagrammatically illustrated in Fig. 6, the solution dehydrator pans 4| are shown as extending an equal amount to the left of each above adjacent pan in the same manner as the extension to the right, as shown in Fig. 1. The air has an unobstructed passage through the particle dehydrator but the contacting walls are fiat surfaced rather'than corrugated as shown in Fig.4.

In the modification illustrated in Fig. 7 two separate enclosures A and B subject to different air conditions, the relative humidity being higher in room A than in room B, are shown connected in parallel into the conditioning system in such a manner that the return air from the enclosure A and fresh outside air may be simultaneously or independently mixed and introduced into the main inlet conduit I l of the conditioning'unit; the return air from the second enclosure being regulably admitted into the blending zone 68 and the conditioned air conducted into both' enclosures. and 83 may be cooled by evaporation by means of any conventional atmospheric cooling tower or spray pond.

In the modification illustrated in Fig. 8, the relative humidity being lower in room D than in Also the cooling water for the coils 32 room ('3, air may be conducted in the same manner from the compartment C into the entrance of the conditioning unit, but the air from the compartment D is conducted directly into the compartment 59 after the complete dehumidification step.

The modification illustrated in Fig. 9 is a sort of combination between the systems disclosed in Figs-7 and 8 and in this modification return air from one enclosure is conducted to the main inlet conduit and the other enclosure is provided with a branch return conduit whereby a portion or all of the air may be fed into the blending zone 60 or into the final zone 59. A continuous cooling unit such as a refrigerating system, is diagrammatically illustrated asat l I l.

It will thus be seen that I have provided air conditioning mechanism' the various parts of which operate in true combination with each other. One element of the combination being the method of combining the hygroscopic element with the thermotactic element to regulate relative humidity over a wide range of temperature, in combination with means for preventing the air from becoming too dry and providing for increasing the humidity by a separate means set for a minimum humidity condition. The precooling coil is a dehydrating coil when the dew point temperature of the air (which varies from 30 to 80 degrees during the summer months) is above the temperature .of the water supplied to the coil. The purpose of this precooler when operating only as a precooler beingto increase the relative humidity (without changing the absolute humidity or moisture content of the air) to conserve hygroscopic material and to cone trol dehumidification. The waste water from this precooling coil is very effective in removing heat from the unit.

It will also be seen that the hydgroscopi c solubreaking up the hygroscopic solution. Furthermore, by completely separating the hygroscopic material zone and solution zone results in dehumidifying the dampest air in a zone of high vapor pressure and then complete the dehumidification by passing the driest air in contact with the material of greatest absorbingvalue and relatively low vapor pressure.

The steps of blending with air of a lower relative humidity after dehydration is to keep an air of a higher relative humidity in contact with the hygroscopic solution to conserve material. If air of a lower relative humidity is mixed with air of a higher relative humidity previous to the first dehydration it reduces the average relative humidity of the entering air.

Return air having a high moisture content and requiring dehydrating from one space should be dehydrated before blending with air of a lower moisture content and not requiring dehydration from a second space to keep the dehydrating material in contact with the air of a higher relative humidity to conserve the dehydrating material and in some cases to produce a drier air.

I have found that in mostinstances the compression, moderate cooling, and expansion of the dehydrated air will be sumcient for most comfort purposes. For example, with air entering the compressing unit at 85, it leaves the compressing unit at 94, is cooled to 80 with 78 water and then. upon expanding is lowered to approximately 71. Coolingwater can be cooled to withduced both as to absolute and relative humidity,

and then increasing the temperature to further reduce the relative humidity but at the same time maintaining the same absolute humidity.

It is one accepted theory that the ionic content of the air is reduced by cooling with low temperature cooling units such as mechanical refrigeration units. However, in my present system this loss-is avoided by maintaining normal air temperatures. In absorbing moisture from the air to transform the latent heat-to sensible heat by an absorbing and dissolving hygroscopic agent, a much higher temperature cooling medium can be used and thus maintain the ionic content of the air. I believe my conditioning system is capable of materially ionizing and purifying the air to enhance the freshening, re-

' juvenating and vitalizing qualities of the air. It

has been conclusively demonstrated that a smoke laden or steam laden air will be quickly cleared by my apparatus and it has also been proven that water soluble vapors and vapors soluble in the hygroscopic solution having a vapor pressure higher than that of the hygroscopic material are .readily absorbed by the hygroscopic material.

What I claim is:

'1. The method of dehumidifying a stream of air, which comprises flowing the air first substantially horizontally in one direction and then substantially vertically in one direction in a, plurality of parallel streams, subjecting the horizontally flowing air to a dehumidifying action of relatively high vapor pressure by reason of contact with a hygroscopic solution, and subjecting the substantially vertically flowing air to a dehumidify ing action of relatively low vapor pressure by reason of contact with particles of hygroscopic material.

2. The method of dehumidifying air, which comprises flowing the air stream through a plurality of separate dehumidifying zones of materially different vapor pressures, flowing a hygroscopic material in an opposite direction through said separate zones, and regulating the amount of surface area contact between the air and hygroscopic agent by the condition of the entering air.

3. Air conditioning apparatus comprising a dehumidifying zone-including a plurality of. substantially vertical fixedly positioned baskets having perforate walls and containing particle hygroscopic material, the perforate walls forming unobstructed vertical air passageways between adjacent baskets whereby the air flows vertically and wipes the hygroscopic material without passbaskets positioned within a separate dehumidi fying zone and below the particle hygroscopicadjacent baskets whereby the air flows vertically and wipes the hygroscopic material without passing through the baskets, and one or more members for receiving hygroscopic solution positioned within a separate dehumidifying zone and below the particle hygroscopic baskets, said member or members being horizontally positioned and arranged to cause the solution hygroscopic material to flow in a direction opposite to the air flow.

5. Air conditioning apparatus comprising a dehumidifying zone including a plurality of substantially vertical perforate baskets for containing particle hygroscopic material, the perforate walls of said baskets forming unobstructed air passageways between adjacent baskets whereby the air wipes the hygroscopic material without passing through the baskets, one or more pan members for holding hygroscopic solution positioned within a separate dehumidifying zone and below the perforate baskets, said pan member or members being horizontally positioned and arranged to cause the solution hygroscopic material to flow in a direction opposite to the air flow, a tank positioned beneath the pan members, and notched surfaces along the forward edge of the pan member or members to divide the hygroscopic solution into fine streams before depositing the same in said tank.

6. Air conditioning apparatus comprising a dehumidifying zone including a plurality of substantially vertical perforate baskets for containing particle hygroscopic material, the perforate walls of said baskets forming unobstructed air passageways between adjacent baskets whereby the air wipes the hygroscopic material without passing through the baskets, one or more pan members positioned within a separate dehumidifying zone and below the baskets, said pan member or members being horizontally positioned and arranged to cause the solution hygroscopic material to flow in a direction opposite to the air flow, a tank positioned beneath the pan members, notched surfaces along the forward edge of pan member or members to divide the hygroscopic solution contained therein into fine streams before depositing the same in said tank, and auxiliary water supply means for said tank to prevent the spent material from crystallizing and to prevent clogging of any drainage therefrom.

7. Air conditioning apparatus, comprising a plurality of zones containing hygroscopic material, means for directing the flow of air through all or a portion of said zones and controlling the rate of flow to regulate the relative humidity of the air, and means positioned in contact with the incoming air operably connected to said first named means and comprising in combination compensating thermostatic and hygroscopic elements for regulating the flow of air through said respective zones.

8. Air conditioning apparatus comprising a dehumidifying zone including a plurality of substantially vertical perforate baskets containing particle hygroscopic material, the perforate Walls of said baskets forming unobstructed air passageways between adjacent baskets whereby the air wipes the hygroscopic material without passing through the baskets, one or more pan members positioned within a separate dehumidifying zone and below the baskets containing particle hygroscopic material, said pan member or members being horizontally positioned and arranged to cause the solution hygroscopic material to flow in a direction opposite to the air flow, a tank positioned beneath the pan members, notched surfaces along the forward edge of the pan member or members to divide the hygroscopic solution into fine streams before depositing the same in said tank, and means for supplying a diluent for preventing crystallization of said spent material in said tank.

9. Air conditioning apparatus comprising means providing a second dehumidifying zone for holding relatively dry hygroscopic material, means providing a first dehumidifying zone for holding relatively moist hygroscopic material, means forming a humidifying zone positioned within said first zone and having means for supplying water vapor thereto, and means actuated by the condition of the incoming air for passing the air from one of said dehumidifying zones in contact with said water vapor means to offset any temporary lowering of the relative humidity below a predetermined point.

10. The method of dehumidifying air and regulating such dehumidification, which comprises flowing the air stream through a plurality of separate dehumidifying zones, flowing a hygroscopic material partly as particles and partly in solution in an opposite direction to the air through said separate zones, maintaining a fixed amount of surface area contact between the air and the solution hygroscopic agent in one of said zones, and regulating the amount of surface area contact between the air and the particle hygroscopic material by the condition of the entering air.

11. The method of dehumidifying air and regulating such dehumidification, which comprises flowing the air stream through a plurality of separate zones of materially different vapor pressures, flowing hygroscopic material in an opposite direction to the air through said separate zones, maintaining a fixed velocity of air through the first zone, and regulating the velocity of the air passing through the last zone by the relative humidity of the entering air.

12."I'he method of dehumidifying air which comprises dehydrating hygroscopically all of a certain volume of air from a certain enclosure, said air having a relatively high humidity, blending the treated air with a separate air flow from a second enclosure and having a relatively low humidity, and then further dehydrating hygroscopically all of the air to conserve the quantity of the hygroscopic agent.

13. Air dehumidifying apparatus, comprising a plurality of zones containing hygroscopic material, means for controlling the flow of air through a portion of said zones, and means positioned in contact with the incoming air and comprising in combination compensating thermostatic and hygroscopic elements for regulating the flow of air through a portion of said zones to regulate the relative humidity of said air.

14. Air conditioning apparatus comprising means providing a dehumidifying zone for containing relatively moist hygroscopic material, means providing a second dehumidifying zone for containing relatively dry hygroscopic material, means for forming a humidifying zone, means actuated by the relative humidity of the incoming zone to offset any temporary lowering of the relative humidity below a predetermined point.

air to control the flow of air through said means providing a second dehumidifying zone, said means for forming a humidifying zone being rendered operative by'the absolute humidity of the incoming air to ofiset any temporary lowering of the absolute humidity of the air below a predetermined point. 15. Air conditioning apparatus comprisin means providing a second dehumidifying zone forcontaining relatively dry hygroscopic material, means providing a first dehumidifying zone for containing relatively moist hygroscopic material, means providing a humidifying zone positioned adjacent said first zone and means for supplying water vapor thereto, and means actu-' ated by the condition of the incoming air for directing the air from one of said means providing a dehumidifying zone to said humidifying 16. The method of conditioning air for a plurality of different compartments one of which contains air having a relatively low humidity,

which comprises dehydrating hygroscopically all of a certain volume of air from a compartment containing air having a relatively high humidity,

high humidity, blending this treated air with another separate volume of air from a compartment containing air having a relatively low humidity,

then further dehydrating hygroscopically the resulting mixture to control the humidity only thereof.

18. The method of controlling the temperature and humidity of air, which comprises converting latent heat into sensible heat by means of hygroscopic dehydration in two steps and, regulating the rate thereof by maintaining a fixed velocity of air in the first hygroscopic dehydration step and varying the velocity of the air in the second hygroscopic dehydration step to control humidity, and removing sensible heat by means of indirect cooling and regulating the rate of said heat removal to control temperature.

19. The method of conditioning air, which com prises removing sensible and latent heat by means of indirect cooling and in converting latent heat into sensible heat by means of hygroscopic dehydration in two steps, and regulating the rate thereof by maintaining a fixed velocity of air in the first hygroscopic dehydration step and varying the velocity of the air in the second hygroscopic dehydration step 'to control the humidity of the 20. Air conditioning apparatus comprising an inlet for air to be conditioned, a relative humidity control positioned subject to the air to be conditioned, a main dehumidifying zone containing a hygroscopic material, an auxiliary dehumidifying zone arranged to receive hygroscopic material in solution form from said main zone, a blending zone intermediate the two zones, an outlet for the conditioned air, adjustable means for directing the passage of air from said inlet to said through said outlet, said adjustable means being" capable of directing air along one of said paths or along both of said,paths simultaneously.

21. Air conditioning apparatus comprising a dehumidifying zone including a plurality of substantially vertical fixedly positioned baskets having perforate walls and containing particle hygroscopic material, the perforate walls forming unobstructed vertical air passageways between adjacent baskets whereby the air flows vertically and wipes the hygroscopic material without passing through the baskets, and means positioned beneath said baskets for directly receiving partially dissolved hygroscopic material from each of said vertical baskets.

22. The method of dehumidifying a stream of air, which comprises flowing of the air first substantially horizontally in one direction and then substantially vertically in one direction in a plurality of vertical substantially unobstructed parallel streams, subjecting the horizontally flowing air to a dehumidifying action of relativelyj high vapor pressure by reason of contact with a hygroscopic solution, subjecting the substantially vertically flowing air to a dehumidifying action of relatively low vapor pressure by reason of contact with particles of hygroscopic material, and flowing the dehumidifying agent used in the dehumidifying action first substantially vertically and then substantially horizontally in a counterflow motion to said air.

23. Air conditioning apparatus comprising a dehumidifying zone including a plurality of substantially vertical perforate baskets for containing particle hygroscopic material, the perforate walls of said baskets forming unobstructed, substantially vertical, air passageways between adjacent baskets whereby the air flows vertically and wipes the hygroscopicmaterial, and'a plurality of 'spaced, substantially. horizontal, superimposed members for receiving hygroscopic solution posi- 

